Adding a block wall to your home can add privacy and provide noise reduction. It is a labour-intensive project, but still within reach of a motivated homeowner that wants to tackle the project himself.
Use a chalk line or surveying paint to mark the centre line of the wall's planned span on the ground. Drive two stakes at each end of the line, 12 inches on either side of the line. Run two strings parallel to one another between the stakes. This will serve as a rough guide when digging the footing.
Dig a footing for the wall that is 18 inches deep (in cold climates, 24 inches) and 24 inches wide, plus a little working room on both sides. Compact the soil firmly using a hand tamper. Use 2-by-4 inch lumber to frame concrete forms to the 18-by-24 dimensions above. Pour concrete into the footing to the tops of the 2-by-4 forms, and carefully level the surface in all directions with a finishing trowel. Let the concrete cure.
Remove the stakes and string guides for the footing. Make a new guideline for laying the blocks by driving stakes at either end of the span, and away from the centre line half the width of the blocks you will be using. Tie masonry string between the strings at a height above the ground that is the same as the height of your blocks, and pull taut. This will put the guideline one row high and along the planned front edge of the wall.
Start at one end and lay down mortar on the footing that is 3 inches deep, the width of the block, and about 3 feet long. Carefully set the first block into place in the mortar, making sure it is in alignment with the guideline. Use the handle of your trowel to tap the brick down to level, using a torpedo level to check it.
Use the towel to spread a 3/8-inch-thick layer of mortar on the end of the first brick. Lay the next brick into place, pressing against the first and the mortar, and in alignment with the guideline. Repeat this process to complete the first row of the wall. Allow the mortar to cure on this first row before continuing to the next.
Raise the guideline the distance of one block's height so that you may use it for the second row. Begin the second row at the same end you started the first row. Use a half block for the first block in the row this time so that the mortar joints are staggered. Otherwise, lay the block with mortar in the same way you did the first row. Continue this process for all succeeding rows. Use a cap block for the final top row.
To allow for water runoff to escape, drill 1-inch holes in some block at ground level, and insert 1-inch PVC pipe.
For walls over 5 to 6 feet, consider using rebar in the wall for strength. Check all local codes and covenants before building.